1. Field of the Invention
The present invention relates to a floating lens barrel, a lens barrel, and a lens barrel system for common use.
2. Description of the Related Art
In a known floating lens system, especially for spherical aberration correction, a focusing lens group is split into a front lens group and a rear lens group, so that a slight relative movement of the front lens group and the rear lens group occurs upon focusing in accordance with the object distance. Hitherto, it has been necessary for a lens barrel for the floating lens system to be provided with a plurality of concentric helicoids whose center is located on the optical axis, so that the relative movement takes place between the front and rear lens groups in accordance with the rotation of a distance adjusting ring which is driven by the power for the focusing operation. However, a lens barrel using a plurality of helicoids has many drawbacks: the drive torque is increased, a deviation tends to occur between the axes of the front and rear lens groups, the distance between the front and rear lens groups tends to change during the assembly, it is difficult to adjust the distance between the front and rear lens groups, and it is difficult to adjust the flange back (FB).